How to test a sufficient or a necessary condition with a case study

Testing sufficient and necessary conditions

5.1 How to test a sufficient or a necessary condition with a case study

Anexo 1: Ejercicios de la intervención

MOVIMIENTOS DE CABEZA Y OJOS PARA REALIZAR SENTADO

1. Con la cabeza quieta mire hacia arriba y luego hacia abajo, primero lentamente y luego rápido. 20 veces.

2. Con la cabeza quieta mire de lado a lado, primero lentamente y luego rápido. 20 veces.

3. Mantenga un dedo en alto con el brazo extendido (a unos 38 cm de la nariz), enfoque su dedo y acérquelo a la nariz y luego a la posición original. 20 veces.

4. Incline la cabeza de lado a lado con los ojos abiertos, primero lentamente y luego rápido (20 veces).Repita con los ojos cerrados cuando mejore el desequilibrio.

5. Gire la cabeza de lado a lado. Primero 2 giros lentos y luego 2 rápidos. Esperar unos

segundos y hacer 3 rápidos. Repetir con ojos cerrados.

6. Mueva la cabeza hacia adelante y hacia atrás con los ojos abiertos, primero lentamente y luego rápido (20 veces).

138

MOVIMIENTOS DE BRAZO Y CUERPO PARA REALIZAR ESTÁ SENTADO

1. Coloque un objeto en el suelo delante de usted, alcáncelo para agarrarlo y luego retorne a la posición sentada, recuerde mirar hacia abajo al objeto y luego subir la vista al incorporarse. 20 veces.

2. Girar la cintura a la derecha y luego a la izquierda, 20 veces.

139

EJERCICIOS PARA REALIZAR DE PIE

1. Pasar de sentado a ponerse de pie y retorne a la posición sentado. 20 veces. Repetir con los ojos cerrados.

2. Repita el número 1 dando una vuelta completa antes de sentarse de nuevo (10 veces con los ojos abiertos).

4. Inclinarse hacia delante y pasarse una pelota u otro objeto similar de mano a mano por detrás de la rodilla.20 veces. Repetir con los ojos cerrados.

140

EJERCICIOS EN MOVIMIENTO

1. Subir y bajar (caminando hacia delante) de una plataforma o de una caja (10 veces con ojos abiertos y 10 con ojos cerrados).

2. Caminar alrededor de una silla (10 veces con ojos abiertos y 10 con ojos cerrados).

3. Lance una bola a otra persona hacia delante y luego hacia atrás. Repetir el ejercicio caminando en círculo alrededor de esa persona (20 repeticiones).

. Realizar cualquier juego que suponga pararse o tirar la bola como por ejemplo la petanca, bolos o baloncesto (20

141

Anexo 2: Cuestionario ABC.

Para cada una de las siguientes actividades, por favor indique su nivel de seguridad o confianza en sí mismo/a, escogiendo un número (porcentaje) de la siguiente escala de valoración:

0% 10 20 30 40 50 60 70 80 90 100%

Ninguna confianza

Confianza total

“Valore cuanta confianza tiene en que NO perderá el equilibrio o se sentirá inestabilidad cuando

:”

1. Pasea por su casa __________%

2. Sube o baja escaleras __________%

3. Se agacha a coger una zapatilla del suelo del

armario. __________%

4 Coge una lata pequeña de una estantería que se

encuentra al nivel de los ojos. __________%

5. Se pone de puntillas para coger algo que se

encuentra por encima de la cabeza. __________%

6. Se sube en una silla para coger algo __________%

7. Barre el suelo __________%

8. Sale de la casa para subirse a un coche. __________%

9. Sube o baja del coche __________%

10. Camina por el aparcamiento de un centro

comercial. __________%

11. Sube o baja una rampa o pendiente. __________%

12. Camina en un centro comercial concurrido/lleno de gente y la gente se le cruza con rapidez

__________% 13. Choca con la gente mientras anda por un centro

comercial. __________%

14. Sube o baja las escaleras mecánicas apoyándose

en el pasamanos __________%

15. Sube o baja las escaleras mecánicas mientras lleva paquetes y no puede apoyarse en los

pasamanos. __________%

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Anexo 3: Cuestionario UCLA-DQ.

Por favor complete todas las afirmaciones siguientes. Marque con un círculo la respuesta que mejor describa su vértigo. Dé una sola contestación por cada afirmación.

I. Tengo vértigo:

1. Raramente 2. A veces

3. Aproximadamente la mitad del tiempo 4. Normalmente

5. Siempre

II. Cuando tengo vértigo, mis síntomas son: 1. Muy leves

2. Leves 3. Moderados 4. Algo graves 5. Graves

III. Cuando tengo vértigo, afecta a mis actividades diarias tales como trabajar, conducir, hacer la compra, cuidar de la familia, cuidar de mí mismo, de la siguiente forma:

1. No me afecta en absoluto

2. Sigo realizando mis actividades diarias sin cambios aunque tengo en cuenta mi vértigo.

3. Sigo realizando la mayoría de mis actividades diarias aunque tengo en cuenta mi vértigo.

4. Sigo realizando mis actividades diarias pero el vértigo me imposibilita seguir cumpliendo con la mayoría de mis responsabilidades.

5. No soy capaz de seguir realizando mis actividades diarias.

IV. ¿Cómo influye mi problema en mi calidad global de vida? Ejemplos: participar en actividades sociales, mantener relaciones íntimas, hacer planes para el futuro, obtener y mantener un puesto de trabajo y participar en actividades de ocio:

143

1. Mi problema no influye para nada en mi calidad global de vida.

2. Mi problema influye algo en mi calidad global de vida. 3. Mi problema influye de una manera moderada en mi

calidad global de vida.

4. Mi problema influye de forma importante en mi calidad global de vida.

5. Mi problema influye de forma decisiva en mi calidad global de vida.

V. Por lo que se refiere a mi miedo a la posibilidad de sufrir de vértigo: 1. Nunca me preocupa la posibilidad de sufrir de vértigo. 2. Raramente me preocupa la posibilidad de sufrir de

vértigo.

3. A veces me preocupa la posibilidad de sufrir de vértigo. 4. Frecuentemente me preocupa la posibilidad de sufrir de

vértigo.

144

Anexo 4: Cuestionario DHI.

Instrucciones: el propósito de ésta escala es identificar las dificultades que usted pueda experimentar debido a su vértigo o falta de equilibrio. Por favor conteste “si”, “no” o “a veces” a cada pregunta. Conteste a cada una de las preguntas según se refieran al problema de su vértigo o falta de equilibrio.

P1. ¿Levantar la vista aumenta su problema?

E2. ¿Se siente frustrado a causa de su problema?

F3. A causa de su problema ¿decide limitar sus viajes de negocios o de ocio?

P4. ¿Caminar por el pasillo de un supermercado aumenta su problema?

F5. A causa de su problema ¿experimenta dificultades al acostarse y levantarse de la cama?

F6. ¿Su problema limita de forma significativa su participación en actividades de ocio tales como cenar fuera de casa, ir al cine, ir a bailar o ir a fiestas?

F7. A causa de su problema ¿experimenta dificultades al leer?

P8. ¿Realizar actividades más exigentes tales como hacer deporte, bailar, o realizar trabajos domésticos (por ejemplo barrer o recoger los platos) aumenta su problema?

E9. A causa de su problema ¿tiene miedo a salir de casa sin que nadie le acompañe?

E10. A causa de su problema ¿ha sentido vergüenza delante de otros?

P11. ¿Los movimientos rápidos de cabeza aumentan su problema?

F12. A causa de su problema ¿evita las alturas?

P13. ¿Aumenta su problema al darse la vuelta en la cama?

F14. A causa de su problema ¿le resulta difícil realizar trabajos domésticos agotadores?

E15. A causa de su problema ¿tiene miedo a que la gente piense que está ebrio?

F16. A causa de su problema ¿le resulta difícil pasear solo?

P17. ¿Caminar por la acera aumenta su problema?

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F19. A causa de su problema ¿le resulta difícil caminar por su casa a oscuras?

E20. A causa de su problema ¿tiene miedo a quedarse solo en casa?

E21. A causa de su problema ¿se siente deprimido?

E22. ¿Su problema ha dificultado las relaciones con sus familiares o amigos?

E23. Influye negativamente su problema en sus responsabilidades domésticas o laborales?

F24. ¿Su problema interfiere en su trabajo o en sus responsabilidades de familia?

146

Anexo 5 : Montilla-Ibáñez A, Martínez-Amat A, Lomas-Vega R, Cruz-Díaz D, Torre-Cruz MJ, Casuso-Pérez R, Hita-Contreras F. The Activities-specific Balance Confidence scale: reliability and validity in Spanish patients with vestibular disorders. Disabil Rehabil. 2016 Mar 23:1-7. [Epub ahead of print].

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Disability and Rehabilitation

ISSN: 0963-8288 (Print) 1464-5165 (Online) Journal homepage: http://www.tandfonline.com/loi/idre20

The Activities-specific Balance Confidence scale:

reliability and validity in Spanish patients with

vestibular disorders

Alharilla Montilla-Ibáñez, Antonio Martínez-Amat, Rafael Lomas-Vega, David Cruz-Díaz, Manuel J. De la Torre-Cruz, Rafael Casuso-Pérez & Fidel Hita- Contreras

To cite this article: Alharilla Montilla-Ibáñez, Antonio Martínez-Amat, Rafael Lomas-Vega, David

Cruz-Díaz, Manuel J. De la Torre-Cruz, Rafael Casuso-Pérez & Fidel Hita-Contreras (2016): The Activities-specific Balance Confidence scale: reliability and validity in Spanish patients with vestibular disorders, Disability and Rehabilitation, DOI: 10.3109/09638288.2016.1161087

To link to this article: http://dx.doi.org/10.3109/09638288.2016.1161087

Published online: 23 Mar 2016.

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ORIGINAL ARTICLE

The Activities-specific Balance Confidence scale: reliability and validity in Spanish

patients with vestibular disorders

Alharilla Montilla-Iba~neza,Antonio Martınez-Amata,Rafael Lomas-Vegaa,David Cruz-Dıaza,

Manuel J. De la Torre-Cruzb,Rafael Casuso-PerezaandFidel Hita-Contrerasa a

Department of Health Sciences, Faculty of Health Sciences, University of Jaen, Jaen, Spain;bDepartment of Psychology, University of Jaen, Jaen, Spain

ABSTRACT

Purpose: To examine the reliability and validity of the Spanish version of the Activities-specific Balance Confidence scale (ABC-S), and its ability to discriminate between patients with and without a history of falls among a Spanish population with vestibular disorders. Method: A total of 84 participants completed the ABC-S. Internal consistency, test–retest reliability and construct validity (exploratory factor analysis) were analysed. Concurrent validity was evaluated using the 12-item Short Form Health Survey (SF-12) and the Dizziness Handicap Inventory (DHI). To determine the accuracy of the ABC total score in discriminating patients with and without a history of falls, a receiver operating characteristic (ROC) curve analysis was performed. Results: The ABC-S showed excellent internal consistency (Cronbach’s a¼ 0.916) and substantial test–retest reliability (ICC¼ 0.86, 95% CI: 0.74–0.93), with standard error and minimal detectable change values of 8.64 and 16.94, respectively. Factor analyses suggested a three-factor structure (explained vari- ance was 62.24%). The ABC total score significantly correlated with the physical component summary score of the SF-12 and with the DHI-P, DHI-E, DHI-F and DHI total scores (p < 0.001). The ABC-S was significantly able to discriminate between participants with and without a history of falls (p < 0.006). Conclusions: The ABC-S is a valid and reliable instrument, suitable to assess balance confidence in Spanish patients with vestibular disorders.

äIMPLICATIONS FOR REHABILITATION

The Spanish version of the ABC scale is a valid and reliable measure of balance confidence in patients with vestibular disorders.

In persons with vestibular disorders, the Spanish version of the ABC scale has shown the ability to discriminate between patients with and without a history of falls in the last year.

ARTICLE HISTORY

Received 12 November 2015 Revised 25 February 2016 Accepted 29 February 2016 Published online 22 March 2016

KEYWORDS

Activities-specific Balance Confidence scale; factor analysis; reliability; Spanish version; validity

Introduction

Falls and their related injuries are among the principal public health concerns for people of all ages, and are considered to be the second leading cause of death from unintentional injury after road traffic accidents.[1] Several risk factors related to falls have been identified, including the fear of falling and postural balance disturbances.[2] Fear of falling is associated with an increased risk of falling and with the restriction and avoidance of certain activities in order to prevent falls, and it may lead to debilitation, increased handicap and disability.[3]

People with vestibular disorders may have limited capacity to perform essential daily activities such as running errands, walking alone, driving and shopping, all because of their fear of falling and their avoidance of movement.[4] Peripheral vestibular diseases are known to induce balance problems and increase the risk of falls.[5,6] Balance impairment has been shown to be directly related to risk of falling in several populations such as noninstitu- tionalized American older adults [7] or postmenopausal women,[8] and balance training programs have proven their effectiveness in improving postural control, functional ability, decreasing the risk of falling in unsteady elderly people.[9]

The term ‘‘balance self-efficacy’’ describes the confidence in handling situations that may lead to a fall.[10] The Activities-specific Balance Confidence scale (ABC) is a commonly used measure of subjective balance confidence and fear of falling.[4] It has been used in several populations, such as community-dwelling people,[11] individuals with chronic stroke [12] and Parkinson’s disease,[13] as well as with patients with peripheral vestibular disease.[14] The original version of the ABC scale was developed by Powell and Myers [15] for older Canadian adults, and has been used to assess the subjects’ level of confidence in performing specific activities without losing balance or becoming unsteady. To this day, the ABC has been translated and validated for several lan- guages and populations [16–18] but, to our knowledge, no valid- ation of its psychometric properties has been carried out in Spanish patients with vestibular disorders.

Based on these facts, the goal of our study was to develop a Spanish version of the ABC-S by assessing its psychometric properties, including internal consistency, test–retest reliability and concurrent validity. In addition, we set out to assess the ability of the ABC-S to discriminate between patients with and without a history of falls in the previous 12 months among a Spanish population with vestibular disorders.

CONTACTProfessor Fidel Hita-Contreras [email protected] Department of Health Sciences, Faculty of Health Sciences, University of Jaen, E-23071 Jaen, Spain

ß 2016 Informa UK Limited, trading as Taylor & Francis Group

DISABILITY AND REHABILITATION, 2016 http://dx.doi.org/10.3109/09638288.2016.1161087

Methods

Participants

This study took place from July 2013 to December 2013. After approaching 95 individuals who received medical attention in oto- rhinolaryngology services of Eastern Andalusia because of unilat- eral vestibular diseases (subacute or chronic), 84 of them volunteered for this analysis. Their diagnoses were: benign parox- ysmal positional vertigo (n¼ 37), Meniere’s disease (n ¼ 16), nonspecific dizziness (n¼ 19), vestibular neuritis (n ¼ 8) and migraine-associated vertigo (n¼ 4). Before filling out the questionnaires, they were interviewed in order to collect information about concomitant diseases (hypertension, hypothyroidism, tinnitus and anxiety) and sociodemographic data such as sex, age, smoking habits and marital status. Educational level was classified into lower-, medium- and higher-education groups on the basis of self- administered questionnaires.[19] Falls were defined as ‘‘an unex- pected event in which the participant comes to rest on the ground, floor, or lower level’’ [20] and the question ‘‘Have you experienced a fall to the ground in the last 12 months?’’ was used to collect the participants’ history of falls.

The sample size of this study was considered appropriate according to psychometric recommendations described by Hobart et al.,[21] and is similar to the sample size used by Hsu and Miller.[22] This study was approved by the Ethical Committee of the University of Jaen, Spain. All participants provided written informed consent to participate in this study, which was con- ducted in accordance with the Declaration of Helsinki, good clinical practices, and all applicable laws and regulations.

Individuals with vestibular disorders and capable of understand- ing and completing the questionnaire were included in the study. Subjects with previous stroke or other neurological disease, signifi- cant visual, somatosensorial or orthopaedic disorders were excluded, as they were taking vestibular sedatives or other central nervous system depressants.

Questionnaires

At first, the English version of the ABC-S was independently translated into Spanish by two bilingual experts working together with clinical professionals who were familiar with the topic and with this type of research. Then, the translators and investigators reached a consensus in a meeting upon a preliminary common forward translation. In the next stage, two bilingual experts translated the Spanish version back into English. The English-translated contents were then compared by the investigators with the original English-version ABC-S to verify whether they had achieved semantic, linguistic, conceptual and technical equivalence. Finally, in order to test the viability, the Spanish version of the questionnaire was then completed by 20 participants in order to verify that they were able to understand the instructions, questions and answering options. The time required to complete the questionnaire was 7–10 min.

The ABC-S is a 16-item questionnaire with 11-point subscales that assess the level of confidence in performing a specific task without losing balance or becoming unsteady. Each item score ranges from 0% (no confidence) to 100% (total confidence) and the total score of the ABC-S is obtained by adding up the ratings (0–160) and then dividing by 16. In the process of cross-cultural adaptation of the Spanish ABC-S, item 8 has been modified to accommodate cultural differences. Four weeks later, the ABC-S was again completed by 31 participants randomly chosen at otorhino- laryngology practices. These results were used to evaluate

test–retest reliability. There were no missing items in any of the self-rating scales.

The 12-item Short Form Health Survey (SF-12) [23] is a multi- purpose, generic, 12-item questionnaire developed from the Short Form Health Survey 36 (SF-36). The SF-12 generates a Physical Component Summary scale score (PCS-SF12) and a Mental Component Summary scale score (MCS-SF12). It has been validated for use in Spanish populations [24] and several studies have reported its validity and reliability as a measure of health-related quality of life in different populations.[25] The number of response options ranges from 3 to 6 depending on the item, and each question is assigned a value that is then converted to a 0–100 scale, where 0 identifies the worst and 100 the best health status.[26]

The Dizziness Handicap Inventory (DHI), developed by Jacobson and Newman in 1990 [27] and culturally adapted to Spanish populations,[28] is a multidimensional self-assessment scale that quanti- fies the level of disability and handicap in three subscales: physical (DHI-P), emotional (DHI-E) and functional (DHI-F). It is possible to use the total score and the scores of the three subscales separ- ately. Scores range from 0 to 100, where a score of 100 indicates a high level of disability and handicap from symptoms of dizziness.

Statistical analysis

Data were described using mean and standard deviation (SD) for the continuous variables, and frequencies and percentages for the categorical variables. The Kolmogorov–Smirnov test and the Levene test were used to test normality of the data in each group and homoscedasticity between samples, respectively. For data management and analysis, the SPSS 19.0 statistical package (SPSS Inc., Chicago, IL) and MedCalc 14.0 (MedCalc Software, Inc., Mariakerke, Belgium) were used. The level of statistical significance was set at p < 0.05. Cronbach’s a coefficient was used to assess the internal consistency of the instrument. Values between 0.70 and 0.95 were considered acceptable.[29] Floor and ceiling effects were evaluated by determining the proportion of subjects scoring the minimum (0) or maximum (100). These effects were considered to be present when 15% of the subjects obtained either the minimum or maximum possible score. Test–retest reliability was deter- mined using Intraclass Correlation Coefficient (ICC2,1). Reliability was considered poor when the ICC was <0.40, moderate between 0.40 and 0.75, substantial between 0.75 and 0.90 and excellent when ICC > 0.90.[30] To analyse the precision of the score, the Standard Error of Measurement (SEM) was calculated as SD at baseline (rbase) minus the square root of (1Rxx), where Rxx is the test–retest reliability index (ICC).[31] In addition, we quantified the minimal detectable change at the 95% confidence level (MDC95)_{ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi}from the SEM formula as MDC95¼ 1:96 rbase

1 ICCÞ p

where 1.96 is the z value corresponding to the confidence interval (CI) of 95%. The MDC provides a good tool to trans- late the ICC into units of change in the instrument. In addition, Bland–Altman plots were performed to assess the limits of agree- ment.[32] Construct validity was assessed using exploratory factor- ial analysis of the scores of the ABC-S items. Concurrent validity was obtained by comparing the ABC-S with the Spanish versions

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